Swim-in-place pools are now well known, at least in the Sun Belt states. The concept is similar to ride-in-place bicycles or, for that matter, to the use of a wind tunnel to test an airplane. That is, the swimmer stays in essentially a fixed position while the water in which he is suspended is pumped past him in a continuous stream.
As known in present commercial products, the swim-in-place pool is provided by circulating water in only one particular direction while the swimmer's body is oriented to swim in the opposite direction, i.e., upstream. The water circulation is conventionally accomplished by means of a pipe loop within which a pump is located, the pump being driven by an electric motor.
Some manufacturers presently manufacture a swim-in-place pool in the form of a large plastic bathtub whose length is in excess of ten feet. The pipe loop is located exterior to the tube and is connected to the respective ends of the tub. The pipes are generally two or three inches in diameter, and the motor rating is in the approximate range of eight to ten horsepower.
In the conventional technology the incoming stream of water which the swimmer confronts is essentially in the form of a jet. It is necessary for the swimmer, in effect, to position himself on top of the jet stream, since water on both sides of the stream is relatively stationery. Some swimmers tire from this endeavor in a very few minutes. Others find the experience unpleasant.